U.S. patent number 10,773,697 [Application Number 16/342,377] was granted by the patent office on 2020-09-15 for pedal travel simulator and hydraulic block including a pedal travel simulator.
This patent grant is currently assigned to Robert Bosch GmbH. The grantee listed for this patent is Robert Bosch GmbH. Invention is credited to Harald Guggenmos, Simon Hansmann, Martin Hoss, Matthias Mayr, Raynald Sprocq, Andreas Weh.
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United States Patent |
10,773,697 |
Weh , et al. |
September 15, 2020 |
Pedal travel simulator and hydraulic block including a pedal travel
simulator
Abstract
A pedal travel simulator for a hydraulic power vehicle braking
system. For the purpose of adapting to different main brake
cylinders and of changing a spring characteristic curve, a stop is
provided to be pressed into a piston of the pedal travel simulator.
A pressing-in depth of the stop delimits a piston stroke.
Inventors: |
Weh; Andreas (Sulzberg,
DE), Guggenmos; Harald (Immenstadt/Seifen,
DE), Hoss; Martin (Sonthefen, DE), Mayr;
Matthias (Rettenberg, DE), Hansmann; Simon
(Plymouth, MI), Sprocq; Raynald (Esbly, FR) |
Applicant: |
Name |
City |
State |
Country |
Type |
Robert Bosch GmbH |
Stuttgart |
N/A |
DE |
|
|
Assignee: |
Robert Bosch GmbH (Stuttgart,
DE)
|
Family
ID: |
1000005053177 |
Appl.
No.: |
16/342,377 |
Filed: |
September 26, 2017 |
PCT
Filed: |
September 26, 2017 |
PCT No.: |
PCT/EP2017/074384 |
371(c)(1),(2),(4) Date: |
April 16, 2019 |
PCT
Pub. No.: |
WO2018/071182 |
PCT
Pub. Date: |
May 24, 2018 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20190232934 A1 |
Aug 1, 2019 |
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Foreign Application Priority Data
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|
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Nov 16, 2016 [DE] |
|
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10 2016 222 562 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B60T
8/409 (20130101); F15B 15/24 (20130101) |
Current International
Class: |
B60T
8/40 (20060101); F15B 15/24 (20060101) |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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2005112034 |
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Apr 2005 |
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JP |
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2016009968 |
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Jan 2016 |
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WO |
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2016132938 |
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Aug 2016 |
|
WO |
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Other References
International Search Report for PCT/EP2017/074384, dated Dec. 8,
2017. cited by applicant.
|
Primary Examiner: Teka; Abiy
Attorney, Agent or Firm: Norton Rose Fulbright US LLP
Messina; Gerard
Claims
What is claimed is:
1. A pedal travel simulator for a hydraulic power vehicle braking
system, comprising: a piston displaceable in a cylinder by brake
fluid; a piston spring which acts upon the piston against a
displacement of the piston by the brake fluid; and an adjustable
stroke limiter for the piston; wherein the stroke limiter is a stop
accommodated in the piston, the stop being adjustable in its
displacement direction, the piston spring configured to press the
stop against, and in direct contact with, a base of the cylinder in
an unpressurized state of the pedal travel simulator.
2. The pedal travel simulator as recited in claim 1, wherein the
stop is pressed into a receptacle in the piston, the stroke limiter
of the piston of the pedal travel simulator being adjusted by a
pressing-in depth of the stop into the receptacle in the piston,
the pressing-in depth determining a distance of the piston from the
base of the cylinder when the stop is pressed against the base of
the cylinder.
3. The pedal travel simulator as recited in claim 1, wherein the
piston includes an adjustable spacer for the piston spring with
which the piston spring engages.
4. The pedal travel simulator as recited in claim 3, wherein the
spacer for the piston spring does not have an effect on a stroke of
the piston.
5. The pedal travel simulator as recited in claim 3, wherein the
spacer includes a screw connection with the piston with which it is
adjustable with regard to the piston in a displacement direction of
the piston.
6. The pedal travel simulator as recited in claim 5, wherein the
adjustable spacer includes a self-cutting thread.
7. The pedal travel simulator as recited in claim 1, wherein the
stroke limiter is a cylinder pin.
8. The pedal travel simulator as recited in claim 1, wherein the
piston includes a blind hole, the piston accommodating the stop in
the blind hole.
9. A hydraulic block for a hydraulic power vehicle braking system
including a pedal travel simulator, the pedal travel simulator
including a piston displaceable in a cylinder by brake fluid, a
piston spring which acts upon the piston against a displacement of
the cylinder by the brake fluid, and an adjustable stroke limiter
for the piston, wherein the cylinder of the pedal travel simulator
is a hole in the hydraulic block; wherein the stroke limiter is a
stop accommodated in the piston, the stop being adjustable in its
displacement direction, the piston spring configured to press the
stop against, and in direct contact with, a base of the cylinder in
an unpressurized state of the pedal travel simulator.
10. The hydraulic block as recited in claim 9, wherein the
hydraulic block includes a main brake cylinder bore.
11. The hydraulic block as recited in claim 9, wherein the
hydraulic block includes a power cylinder bore.
12. The hydraulic block as recited in claim 9, wherein the piston
includes a thread hole, the piston accommodating the stop in the
thread hole.
13. The hydraulic block as recited in claim 9, wherein the stroke
limiter is a cylinder pin.
14. The hydraulic block as recited in claim 9, wherein the piston
includes a blind hole, the piston accommodating the stop in the
blind hole.
15. The hydraulic block as recited in claim 9, wherein the piston
includes a thread hole, the piston accommodating the stop in the
thread hole.
Description
FIELD
The present invention relates to a pedal travel simulator.
BACKGROUND INFORMATION
In power-actuated hydraulic vehicle braking systems, pedal travel
simulators make a pedal travel (a lever travel in the case of a
parking brake) possible upon actuation of a main brake cylinder. In
the case of a power actuation, the main brake cylinder is used as a
setpoint generator for a hydraulic brake pressure which is not
generated with the aid of the main brake cylinder, but with the aid
of external energy, for example with the aid of a hydraulic pump.
The main brake cylinder is hydraulically separated from the vehicle
braking system in the case of a power brake application, for
example by closing a valve, and displaces brake fluid into the
pedal travel simulator upon actuation.
A pedal travel simulator usually includes a cylinder and a piston,
which is displaceable within the cylinder, as well as a piston
spring which acts upon the piston against a displacement direction.
In the case of a power actuation of a vehicle braking system, the
pedal travel simulator is hydraulically connected to a main brake
cylinder which displaces brake fluid into the cylinder of the pedal
travel simulator upon actuation, whereby the piston is displaced in
the cylinder against a spring force of the piston spring. Here, a
spring rate of the piston spring, i.e. a spring force as a function
of a deflection of the piston spring, essentially determines a
pedal characteristic, i.e., an actuating force as a function of an
actuating path of the main brake cylinder. The pedal travel
simulator may always be hydraulically connected to the main brake
cylinder or become hydraulically connected to and disconnected from
the main brake cylinder by opening and closing a simulator valve.
The deflection of the piston spring is the elastic deformation of
same due to the displacement of the piston in the cylinder which
results in a spring force or a change in a spring force used by the
piston spring to act upon the piston against the displacement.
SUMMARY
An example pedal travel simulator according to the present
invention includes an adjustable stroke limiter for its piston.
With the aid of the stroke limiter, a return stroke of the piston
or a turning point, or a position of the piston in the case of an
unpressurized pedal travel simulator is adjustable. The pedal
travel simulator may thus be adapted to different main brake
cylinders having different diameters and/or different lengths, for
example. A greater stroke of the piston of the pedal travel
simulator is, for example, adjusted for a main brake cylinder
having a larger diameter or a longer piston displacement to be able
to accommodate a larger brake fluid volume from the main brake
cylinder. A characteristic curve of the pedal travel simulator is
also affected by the piston stroke and, in turn, has an effect on a
characteristic curve of the main brake cylinder. The characteristic
curve of the pedal travel simulator is a function of a hydraulic
pressure of the accommodated brake fluid volume. The characteristic
curve of the main brake cylinder, which is also referred to as a
pedal characteristic curve or a pedal characteristic, is a function
of a piston travel or a pedal travel of a piston force or pedal
force.
Advantageous embodiments and refinements of the present invention
are described herein.
One refinement of the present invention which in general may also
be implemented without the adjustable stroke limiter provides for
an adjustable spacer of the piston for a piston spring. The piston
or the pedal travel simulator is thus adaptable to piston springs
of different lengths and a pretension of the piston spring may be
adjusted. Both have an effect on the characteristic curve of the
pedal travel simulator and of a main brake cylinder which is
connected to the pedal travel simulator. Ideally, the spacer does
not change a stroke of the piston, so that the stroke of the piston
and the pretension of the piston spring may be adjusted
independently of one another, i.e., a change in the stroke of the
piston does not change the pretension of the piston spring and vice
versa.
One advantage of the present invention is that different piston
strokes and characteristic curves may be implemented with the same
parts, i.e., without changing the piston, cylinder, and using the
same piston spring.
The pedal travel simulator is preferably integrated into a
hydraulic block of a slip control unit of a hydraulic vehicle
braking system, in particular a power vehicle braking system. Such
hydraulic blocks are conventional; they are usually cuboid-shaped
metal blocks which are drilled according to a hydraulic circuit
diagram of the vehicle braking system or of the slip control unit
of a vehicle braking system. The hydraulic blocks are equipped with
solenoid valves, hydraulic pumps, and other hydraulic components of
the slip control unit. Such hydraulic blocks are conventional and
will not be explained here in greater detail.
BRIEF DESCRIPTION OF THE DRAWING
The present invention is explained in greater detail below on the
basis of one specific embodiment illustrated in the FIGURE.
FIG. 1 shows a longitudinal section of a hydraulic block of a slip
control unit of a hydraulic power vehicle braking system including
a pedal travel simulator according to the present invention.
DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS
Hydraulic block 1 according to the present invention which is
illustrated in FIG. 1 is provided for a slip control unit and a
power actuation of a hydraulic power vehicle braking system which
is incidentally not shown. Hydraulic block 1 is a cuboid-shaped
metal block which is shown without any equipment apart from a pedal
travel simulator 2 to be elucidated. Hydraulic block 1 has a bore
(not visible in the drawing) according to a hydraulic circuit
diagram of the vehicle braking system. It is equipped with
hydraulic components (not in the FIGURE) for the power actuation
and of the slip control unit, such as solenoid valves, a main brake
cylinder including one or multiple pistons, a power cylinder
including a piston, and pedal travel simulator 2 which are
hydraulically interconnected through the bore according to the
hydraulic circuit diagram of the vehicle braking system. Since a
main brake cylinder is integrated into hydraulic block 1, only
hydraulic wheel brakes must be connected to hydraulic block 1 via
the brake lines. Such hydraulic blocks 1 are conventional and will
not be explained here in greater detail.
Hydraulic block 1 has a cylindrical blind hole as cylinder 3 of
pedal travel simulator 2 at whose base 7 a bore 4 merges which
hydraulically connects pedal travel simulator 2 to a main brake
cylinder bore 5. A piston 6 is axially displaceably accommodated in
cylinder 3.
In an orifice of cylinder 3 of pedal travel simulator 2, a
bowl-shaped cylinder cover 9 is screwed in and sealed with the aid
of a sealing ring 10. In cylinder cover 9, a stack of disk springs
11 is situated as piston spring 12, other springs, such as a
helical pressure spring or rubber-elastic spring elements also
being possible as piston spring 12 (not illustrated). In the
exemplary embodiment, four disk spring pairs are stacked in the
form of a disk spring pack in cylinder cover 9, disk springs 11
being oriented alternatingly in the opposite direction, i.e., the
hollow sides and outer sides of disk springs 11 always face one
another alternately. Disk springs 11 are supported in cylinder
cover 9 and act upon piston 6 of pedal travel simulator 2 against
base 7 of cylinder 3.
On its front side facing base 7 of cylinder 3, piston 6 of pedal
travel simulator 2 has a coaxial blind hole into which a cylinder
pin is pressed as stroke limiter 8. In unpressurized pedal travel
simulator 2, stroke limiter 8 of piston spring 12 presses piston 6
against base 7 of cylinder 3. A pressing-in depth of stroke limiter
8 into the blind hole of piston 6 determines a distance of piston 6
from base 7 of cylinder 3 when stroke limiter 8 rests against base
7 of cylinder 3. The pressing-in depth of stroke limiter 8 into the
blind hole of piston 6 establishes a turning point of piston 6 and
a stroke of piston 6 is delimited in a return stroke direction. The
return stroke direction is a displacement of piston 6 in the
direction of base 7 of cylinder 3. The stroke of piston 6 is
adjustable with the aid of the pressing-in depth of stroke limiter
8 into the blind hole in piston 6.
Due to adjustable stroke limiter 8, pedal travel simulator 2 may be
adapted to different main brake cylinders: for example, when
actuating a main brake cylinder having a larger diameter and/or a
longer piston stroke and consequently a greater volume displacement
of brake fluid, stroke limiter 8 of piston 6 of pedal travel
simulator 2 according to the present invention may be pressed
deeper into the blind hole in piston 6 and a greater stroke of
piston 6 may thus be adjusted, so that pedal travel simulator 2 is
capable of accommodating a larger brake fluid volume from the main
brake cylinder.
Stroke limiter 8, which is adjustable in a displacement direction
of piston 6 in cylinder 3 of pedal travel simulator 2, i.e., in a
stroke direction of piston 6, for the purpose of adjusting or
delimiting the stroke of piston 6, may generally also be understood
as stop 13 of or for piston 6. Base 7 of cylinder 3 may also be
understood as an abutment 14 for stop 13. The blind hole in piston
6, into which the cylinder pin forming stroke limiter 8 or stop 13
is pressed, may also be understood as an accommodation for stroke
limiter 8 or stop 13. As already elucidated above, the turning
point of piston 6 is established and stroke limiter 8 adjusted as a
result of the pressing-in depth of stroke limiter 8 or stop 13 into
the blind hole in piston 6. A cylinder pin which is pressed into a
blind hole in piston 6 is not necessarily an adjustable stroke
limiter. There are other possible applications, for example a
stroke limiter may be screwed into a thread hole in the piston and
be adjustable with the aid of screws (not illustrated). An
adjustable stroke limiter may also be provided in cylinder 3, for
example at base 7 of cylinder 3, instead of at piston 6 (not
illustrated).
On a front side opposite, i.e. facing, piston spring 12, piston 6
of pedal travel simulator 2 has a further coaxial blind hole 15
into which a threaded bolt is screwed as spacer 16. Blind hole 15
does not have a thread until spacer 16 is screwed in; spacer 16 has
a self-cutting thread 17 which cuts for itself a counter-thread
into blind hole 15 in piston 6. Thread 17 of spacer 16 and the
counter-thread form a screw connection 18 through which spacer 16
is shiftable and adjustable in the displacement direction or stroke
direction of piston 6. Due to its self-cutting thread 17, spacer 16
is held in a clamped manner against rotation in blind hole 15 in
piston 6, so that spacer 16 does not rotate on its own and does not
shift inadvertently. Other possible applications for spacer 16 and
its adjustability are also possible in this case.
Piston spring 12 presses against spacer 16 and acts upon piston 6
via spacer 16. Spacer 16 may be used to adjust a distance between
piston spring 12 and piston 6 and thus, for example, a pretension
of piston spring 12. Moreover, adjustable spacer 16 enables an
adaption to different piston springs 12; for example, piston
springs 12 of different lengths and cylinder covers 9 of different
lengths may be used. In the case of a disk spring pack, piston
springs 12 of different lengths are possible through a varying
number of disk springs 11. With the aid of adjustable spacer 16 for
piston springs 12 and also adjustable stroke limiter 8 as well as
the changeability of disk springs 11 or piston spring 12 and of
cylinder cover 9, in which piston spring 12 is accommodated, a
characteristic curve of pedal travel simulator 2 according to the
present invention is adjustable. The characteristic curve is a
displacement travel or stroke of piston 6 or a brake fluid volume
accommodation of pedal travel simulator 2 with regard to a
hydraulic pressure of brake fluid in cylinder 3 of pedal travel
simulator 2. The characteristic curve of pedal travel simulator 2
determines a characteristic curve of a main brake cylinder to which
pedal travel simulator 2 is connected in the case of a power
actuation of a hydraulic vehicle braking system. The characteristic
curve of the main brake cylinder is a pedal, lever, or piston
travel with regard to a pedal or lever force upon actuation of the
main brake cylinder.
If the hydraulic vehicle braking system (not illustrated) is
actuated via external power, a main brake cylinder actuatable via
muscle power or non-muscle power is used as the setpoint generator
for a brake pressure to be generated with the aid of external
energy. Upon actuation of the main brake cylinder, the brake fluid
displaced from the main brake cylinder flows through bore 4 in
hydraulic block 1 into cylinder 3 of pedal travel simulator 2,
where it displaces piston 6 against a spring force of piston spring
12. Since in the case of a power actuation of the vehicle braking
system, the main brake cylinder is hydraulically separated from the
vehicle braking system by closing a valve, it cannot displace brake
fluid into the vehicle braking system. Pedal travel simulator 2
makes a piston displacement possible and thus a pedal or lever
travel upon an actuation of the main brake cylinder in the case of
a power actuation of the vehicle braking system.
As already mentioned above, hydraulic block 1 has a main brake
cylinder bore 5 which has a stepped diameter and has
circumferential grooves in the specific embodiment. A main brake
cylinder (not depicted), into which one or multiple piston(s) (not
in the drawing) is/are introduced, of which one is displaceable for
actuating the main brake cylinder or the vehicle braking system
using a (foot) brake pedal (not depicted) or a (hand) brake lever
(not depicted) and of which the other piston(s) is/are displaceable
when acted upon by pressure, is pressed into main brake cylinder
bore 5.
For power actuation, hydraulic block 1 includes a power cylinder
bore 19 which is located in a different section plane than pedal
travel simulator 2 and of which only a half-section is therefore
visible in FIG. 1. The section is offset in such a way that pedal
travel simulator 2 is visible in the axial section and power
cylinder bore 19 is visible as a half-section. A power cylinder
(not depicted), in which a piston is displaceably accommodated, is
pressed into power cylinder bore 19. For a power actuation of the
vehicle braking system, the piston is displaced with the aid of an
electric motor (not depicted) via a reduction gear unit and a screw
drive in the power cylinder. The electric motor is screwed to
hydraulic block 1. In the case of a power actuation, the main brake
cylinder is used, as already mentioned above, as the setpoint
generator; a brake pressure is controlled by controlling a
displacement path of the piston in the power cylinder and/or with
the aid of solenoid valves.
* * * * *